1. Field of the Invention
The present invention relates to a vacuum processing apparatus, particularly, to an improvement in the transfer arm arranged in a load lock chamber used in a processing apparatus of an LCD substrate.
2. Description of the Related Art
In the manufacture of a semiconductor device or a liquid crystal display device (LCD), it was customary to use a so-called multi-chamber type vacuum processing apparatus provided with a plurality of vacuum process chambers in which predetermined treatments such as an etching treatment and an ashing treatment are applied under an atmosphere of a reduced pressure to a semiconductor wafer or an LCD substrate.
In the conventional vacuum processing apparatus of this type, a plurality of, e.g., three, vacuum process chambers are arranged around a preliminary vacuum chamber, i.e., load lock chamber, in which is arranged a substrate transfer mechanism such as a transfer arm. The workpiece such as an LCD substrate or the like is put in each vacuum process chamber by the transfer arm arranged within the load lock chamber for application of a predetermined treatment to the workpiece within the vacuum process chamber. The transfer arm is also utilized for taking the workpiece after the treatment out of the vacuum process chamber.
However, where a single transfer arm is used for transferring the workpiece in and out of the process chamber, the through-put of the vacuum processing apparatus is lowered. To overcome the difficulty, it is proposed to arrange, for example, two transfer arms in two states within a load lock chamber. If a plurality of transfer arms are arranged within the load lock chamber, however, it is unavoidable for the load lock chamber to be enlarged. It is also unavoidable for the vacuum process chamber, into which the transfer arms are inserted, to be enlarged. It follows that the entire vacuum processing apparatus is rendered bulky, leading to an increased manufacturing cost. What should also be noted is that the transfer arm causes dust generation. Naturally, it is not desirable to increase the number of transfer arms.